Electromagnet.



PATENTED MAY 5, 1908 H. ROWNTREB. ELEUTROMAGNET; APPLICATION FILED APR. 6,190 7.

7 Vi/maowo rrnn STLA'IES EXTENT" ori ice.

'- \t'l'i lilXl; (OUPANY. (W (HUI-\Gt). ILLINOIS, A ,(lORPORATlON OF ILLINOIS.

ELECTROMAGNET.

No. 886,870. Specification of Letters Patent. Patented May 5, 1908.

Application filed April 6, 1907. Serial No. 366,650.

To all whom it may concern: longitudinal section of an electro magnet em- 55 Be it known that I, HAROLD ROWNTREE, a bodying the principles of my invention. Fig. citizen of the United States, residing at Chi- 2, is a transverse section on the line 2, 2. cago, in the county of Cook, State oi Illinois, The theoretically perfect alternating curhave made a certain new and useful lnvenrent solenoid is one which is so constructed tion in Electromagnets, of which the followthat the plunger or core is almost entirely 60 ing is a specification. outside the coils or windings at the com- In my pending application, Serial No. mencement of the movement of such core, 266,542, filed June 28, 1905, I have shown, and almost entirely inclosed by the coils or described and claimed broadly a construcwindings at the time of the movement so tion of electro magnet in. the form of a solenthat there may be no induceddeterrent eflect 65 oid. in which the induced current is accenat the outset, and a strong induced effect at tuated as the core or plunger of the solenoid, the end of the movement of the coreinto the r is drawn into the Winding or coils thereof, or coils or windings, which induced effect reto restate the same broad idea, wherein the sults in reducing the amperage or consumpinduced retroactive effect is abnormally intion of the current at that point. This theocreased as the plunger is drawn into the retically perfect condition is dii'ficult to atcoils or windings. While this idea is claimed. tain in practice with the ordinary construcbroadly in my pending application referred tions of solenoids. In the accomplishment to, the particular embodiment therein shown of these desirable objects, in accordance with and described for carrying out my invention my present invention, I propose to provide consists of a Winding or coil arranged in sec means whereby at the beginning of the tions with means normally short circuiting movement of the solenoid plunger or core, it a portion of the sections of such coils or wind-v is subjected to the action of a comparatively .25 ings at the beginning of the movement of the few turns of wire producing a very small incore or plunger into such coils, and the subduced eileot, and at the end of its movement sequent breaking of the short circuit as the into the coils such plunger is subjected to the plunger or core approaches the limit of its action of a large number of turns of the Wire,

movement into the coil. resulting in the production of a strong in 30 The present invention relates to electro duced eiiect.

magnets of ti is nature. In carrying out my present invention I The object of the present invention is to propose to employ a Winding or soil which isprovide another form of embodiment of tapering, as shown in the drawing, that is, means for accomplishing the result set forth the number of turns of the wire around the 35. and claimed broadly in my prior application. coreincrea-ses from one end of the coil to the Another object of my lpresent invention is other. so to im ose a stron ul u )OIl the coreor In the drawin reierence 810T]. A desw P I g P I s e 1' s plunger of tne solenoid. throughout the nates the exteriorly tapering COll or Winding greater portion of its length. for the solenoid; B, the plunger or core, ar-

40 A further object of the invention is to cut ranged to operate Within a non-magnetic down to aminimum the consumption of our tube G. The coil A, is held between the rent after the core or plunger attains the end non-magnetic end plates C, D. In practice of its movement into the coils or windings. I prefer to employ a core orplunger for the Other ob'ects of the invention will appear solenoid made up of laminations or sections. 45 more fully hereinafter. I prefer to employ for this purpose short sec- The invention consists substantially in the tions of soft iron Wire as thereby I am enconstruction, combination, location and arabled to secure better laminating eilect. ran 'ement of parts, all as will be more fully Those laminations are assembled preferably, set 'orth as shownin the accompanyingdrawin aparallcl relation With respect to each 50 ing and finally pointed out in the appended other to form the core or plunger. At one claims. I end the various laminations em loved are 1-05 Referring to the accompanying drawing formed into a closed magnetic circuit with and to the various views and reference signs respect to each otherfor a very short porappearing thereon, Figure 1, is a view in tion of their lengths, as indicated at E. This may be accomplished by brazing, welding or otherwise forming the ends of the laminations into a solid homogeneous mass. For the remaining portions of the lengths of the laminations, said laminations. are in open magnetic circuit other. By employing a laminated core, the laminations being united or joined into a closed magneticcircuit at one end only, I not only avoid noise and chattering when an alternating current is used, but I also avoid undue heating of the core.

In the operation of the electro magnet the closed magnetic circuit end of thelaminations moves toward that end of the coil or winding which has the greater number of turns of wire. In order to concentrate the pull upon such end of the core or plunger, I may, if desired, place the laminated magnet'ic' block F, over or adjacent the larger end of the coil as shown, the smoothed surface of the end E, of the core or plunger, making sufficient contact with the surface of the laminate d magnetic block to prevent lluctuations of the current which mightctherwise cause mechanical vibrations and thereby produce an objectionable noise.

By employing a tapering coilthe number of turns of wire around the plunger at the commencement of the movement of the core into the coil, is less than if the coil was of uniform diameter throughout its length, and, therefore, while the pulling effect exerted by the coil as. a whole upon the core is practically the same as if t is core was of uniform diameter, yet the induced deterrent effect is comparatively small owing to the comparatively few number of turns of wire around the core at the beginning. The number of turns of the wire which surround the core increase more rapidly as the core moves into the coil, in the case of a tapering coil, than in the case of a cylindrical coil. In other words, the number of turns of wire which surround any particular point in the length of the core increase the farther the core is drawn into the coil. By reason of this there is secured a very great increase in the induced deterrent effect, in proportion to the comparatively small deterrent efi'ect at the cournencement of the movement. In other words the object is to have as few turns of wire as possible around the core at the commencement of the movement of the core, and as many turns as possible at the completion of such movement. This object I attain in the present instance by the peculiar shape of the coil, that is, by the tapering form thereof. From the foregoing desc iption it will be seen that the increased induced effect of {K3 current becomes greater in a constant I. as the lunger continues its movement .1 the coi It will also be seen that the effect of the induced action is appliedover increasing length of the core or plunger.

with reference to each? An electric magnet embodying the principles of my, invention is welladapted for use in any situation where the service of a solenoid is required. I do not desire, therefore, to be limited or restricted in respect to the use to which an electro magnet embodying my invention may he put.

An electro magnet embodying the principles of my invention is specially designed for use-in connection with an alternating current, and particularly a one phase current, but I do not desire to be limited or re stricted in this respect.

Variations and changes in the details of construction and arrangement might readily occur to persons skilled'in the art and still fall within the spirit and scope of my invention. I do not desire, therefore, to be lim ited to the exact and specific details shown and described.

Having now set forth the object and nature of my invention and a construction embodying the principles thereof, what I claim as new and useful and of my own invention, and desire to secure by Letters Patent is:

1. In an alternating current solenoid, the combination with a laminated core or plun ger having the laminations thereof united into a solid mass at one end and separated at all other voints, of a coil or winding therefor, said coi increasing from end to end in the'number of turns thereof which surround the core.

2. In an alternating current solenoid a laminated. core or plunger, the laminations being united into a solid mass at one end and in open magnetic circuit at all other oints, and a tapering coil for said core or p unger.

3. In an alternating current solenoid, a laminated core or )lunger, having the lami nations thereof united into a solid mass at one end and in open magnetic circuit with respect to each other at all other points, a tapering coil for said core or plunger, and means arranged at the larger end of said coil for concentrating the pull on saidcore or plunger.

4. In an alternating current solenoid, a laminated core or plunger, said laminations being united together at one end into asolid mass to form a closed magnetic circuit with respect to each other, and disconnected from each other at all other points to form an open magnetic circuit with. respect to each other, and a coil or winding, said coil orwinding increasing in the number of turns thereof from end to end, and means arranged at the end containing the larger number of coils for increasing the induced effect thereof.

In an alternating current solenoid, a laminated core or plunger, having the lami nations united together into a solid mas:- at one end and disconnected at all other points, and a coil, said coil increasing in external hamster towards the end to which the core or plunger is drawn the bore ofgseid'coil being of uniform transverse areaa 6. in an alteri'ieting current solenoid, a laminated core or plunger having the laminations united into solid mass at one end and disconnected at all other points and a coil, said coil increasing in external diameter irom end to end, end a stationary magnetic block arranged adjacent the larger end of" the coil.

in e solenelci, a core and a1 0011, said core lacing lamina ted, the lamination being united 2y together at one end to form a closedgnetic circuit and disconnected to form;

solid in. on n magnetic circuit with reference to each other throughout the renieining portion of" j scent to the end of the coil, having a larger,

number of turns. 7

In an elterneting current solenoid, a

core or plunger composed -of laminations,

said leminstions being united into a solid mass to form a closed magnet circuit at one end for a portion of its lengthyand-ain exteriorly tapering coil into the bore of which said core is adapted to be drawn.

10. In an alternating current solenoid, a laminated core ,or plunger of uniform cross sectional erea throughout its length, said laminations being united into a solid mass to form a closed magnetic circuit atone end onlyfend an exteriorly tapering coil into which the core is adapted to be drawn.

, 11'. In an a ternetmg current solenoid, a laminated core orplun 'er, the laminations being united into a solid mass to. form fa closed magnetic circuit at one end onl and an exteriorly tapering 0011 having a bore of uniform transverse sectional area throughout its length into which the core is adapted I,

to be drawn.

In testimony whereof I have hereunto set my hand in the presence of the subscribing witnesses, on this 28th day of March A. 1907.

4 HAROLD RoWNTnnn' Witnesses:

Josnrn Knew,

S; DARBY. 

